The most successful degradable plastic is PLA, which is a polylactic acid product. Lactic acid is derived from the fermentation of agricultural products. The principle of polylactic acid degradation is due to the unique molecular structure.
Broadly speaking, polylactic acid is not an agglomerate of olefins, and there are a large number of ester bonds in the main chain. Unlike polyester materials such as PET, since the carbon chain is too short, it does not protect the active ester bond. It is not resistant to electrophiles or nucleophiles. In other words, it can be destroyed by anionic cations. It can be corroded by acid or alkali. Considering biological fermentation is also a chemical reaction. The weakest link to attack, so polylactic acid exposed to a slightly harsh environment will be vulnerable, the degradation of lactic acid will continue to oxidize until it becomes carbon dioxide and water, which is the basic degradation process. Biodegradation is more complicated, but the basic rhythm is still similar, and it is dissolved into water and carbon dioxide. This kind of plastic can be degraded.
Degradable plastics have a very good prospect, but the biggest problem at the moment is expensive. Solve the problem, but also need to solve the problem of poor performance, anti-fall is not comparable to PC, heat resistance is not comparable to PA, anti-corrosion is not comparable to PE, for most industries, performance is still the primary concern. So the current use is not universal.
At present, the promotion of degradable plastics in agricultural films is a very good attempt. First, there is demand in this area. Second, other performance requirements are not high, and the amount of use is large, which can support the development of the industry; medical products are of course also an important demand area.
For food packaging plastic bags, there is currently no degradable plastic material with good price and good performance. Degradable materials are really popular in the food packaging industry for at least 20 years.
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Post time: Sep-19-2018